30 x 0.4ml single dose units. Thealoz (Preservative Free) Duo Dry Eye drops are an everyday solution for all your Dry Eye symptoms including watery, irritated or gritty eyes. Clinically proven and recommended by experts. Unique formulation provides you with longer lasting relief and protection for up to four hours on the tear film. Easy to use single dose vials, ideal for travelling or occasional use. Suitable for contact lens wearers and are free from chemical preservatives.